Mobile Network Signal bar colors

[RHS]

What do the different colors indicate on the mobile network signal bar under the battery settings? Sometimes it is green, or olive drab or beige.

 

[RHS]

Anybody know the answer?

 

[qisdtech]

I believe it represents the signal strength over time, the green areas represent 4+ bars, 3 is the olive and 1 or 0 bars is red.